Endocrine profiles and embryo quality in superovulated Japanese Black cattle

The relationships between plasma concentrations of progesterone (P(4)), estradiol-17beta (E(2)) and lutenizing hormone (LH) and embryo yield and quality were examined in 40 superovulated Japanese Black cattle. The results indicated that the ovarian function, especially the function of corpus luteum on the first treatment day, is an important factor for reliable superovulation in cattle. The levels of plasma E(2) and LH at estrus were related to embryo yield and quality.     

Bioenergetics of nerve excitation

The process of action potential production is analyzed in relation to the problem of energy transduction in the nerve. Describing the conditions required for the maintenance of excitability, the indispensability of divalent cations and the dispensability of univalent cations in the external medium are emphasized. Univalent cations with a strong tendency toward hydration enhance the action potential amplitude when added to the external Ca-salt solution. Experimental facts are described in consonance with the macromolecular interpretation of nerve excitation which postulates a transition of the negatively charged membrane macromolecules from a hydrophobic (resting) state to a hydrophilic (excited) state. Thermodynamic implications are discussed in relation to changes in enthalpy and volume accompanied by action potential production. Difficulties associated with analyses of excitation processes on a molecular basis are stressed.     

Further studies of nerve membranes labeled with fluorescent probes

Summary By using the technique of intracellular perfusion combined with fluorescence measurements, the mode of binding of 6-p-toluidinylnaphthalene-2-sulfonate (2–6 TNS) in a squid giant axon was examined. The apparent dissociation constant for the binding sites in axons was found to be roughly 0.22mm. Out of approximately 5×10¹⁴ molecules/cm² of 2–6 TNS bound to the sites in and near the axonal membrane, roughly 2×10¹⁰ molecules/cm² are shown to contribute to a transient decrease in fluorescence during nerve excitation. By recording fluorescence signals with a polarizer and analyzer inserted in four different combinations of orientations, studies were made of the directions of the transition moments of various probe molecules relative to the longitudinal axis of the axon. Among hydrophobic probes examined, the polarization characteristics of the fluorescence signals obtained with 1–8 derivatives of aminonaphthalenesulfonate (1-8 ANS, 1-8 TNS and 1-8 AmNS) were found to be very different from those obtained with 2–6 derivatives (2-6 ANS, 2-6 TNS and 2-6 MANS). A tentative interpretation is proposed to account for this difference in physiological behavior between 1–8 and 2–6 derivatives. It is emphasized that measurements of fluorescence polarization yield significant information concerning the structure of the axonal membrane.     

Removal of the Schwann sheath from the giant nerve fiber of the squid: An electron-microscopic study of the axolemma and associated axoplasmic structures

Summary Surgical thyroidectomies were used as means of altering the thyroid state of adult recipients to study the possible influence of thyroid hormones on fibre formation in irides by immature noradrenaline neurons of the locus coeruleus grafted to the eye. Whole-mount preparations of irides were analysed using fluorescence histochemistry according to Falck-Hillarp, subjectively estimating on a blind basis the number of fibres, their pattern of distribution and individual morphology in the iris dilator plate. Neurones of the locus coeruleus formed nerve fibres in irides of thyroidectomized recipients to the same extent as in controls. Distribution and fine structure of these fibres, however, differed markedly. The numerous thick axon bundles from the attachment of the brain graft, normally seen to radiate out from locus coeruleus-neurones in oculo, were almost totally lacking in the thyroidectomized group. Also, the individual nerve fibres showed abundant peripheral accumulations of fluorescent material. This appearance of the outgrowth of fluorescent fibres in the experimental group, indicative of a disturbed formation of nerve fibres during development in oculo, was abolished by reversal of the thyroid hormone deficiency using daily injections of 1-thyroxin to the recipients throughout the experiment. This strongly indicates a role for thyroxin in the process of formation of nerve fibres originating from the neurones of the locus coeruleus during perinatal development. The present paper is supportive of recent reports claiming that during the development of the CNS thyroxin plays a crucial role in tubulin assembly, and thus presumably for the ability of neurones to form processes.     

Cytotoxic effects of methylnitrosourea on developing brain

The effect of methylnitrosourea (MNU) on cerebellar and cerebral DNA, RNA, protein, lysosomal enzymes (acid DNase, RNase, phosphatase, and beta-glucuronidase), and 2',3'-cyclic nucleotide 3'-phosphohydrolase (2',3'-CNPase) activities was studied in rats from birth through 12 days of age. Subcutaneous injection of MNU in a dose of 0.625 mmol/kg caused a suppression of increase in weights and content of DNA, RNA, and protein of cerebellum, but no changes in those of the cerebrum or in body weight. Ratios of protein and RNA to DNA were substantially elevated by MNU in the cerebellum but not in the cerebrum. Acid DNase and acid RNase activities of MNU-treated rats were significantly elevated beyond the increase of these activities in controls in the cerebellum, but no change in these activities by MNU was observed in the cerebrum. A slight elevation in acid phosphatase activity was observed in the cerebellum but not in the cerebrum after MNU pretreatment. Beta-glucuronidase and 2',3'-CNPase activities were not changed in the cerebellum or in the cerebrum. These results suggest that in the developing brain, especially in the cerebellum at the mitotic stage, MNU caused cell damage and inhibited cell mitosis.     

Effects of Adenosine Receptor Subtypes on Hippocampal Extracellular Serotonin Level and Serotonin Reuptake Activity

Abstract: To clarify the effects of adenosine receptor subtypes (A₁, A₂, and A₃) on hippocampal serotoninergic function, hippocampal extracellular serotonin (5-HT) levels were determined by in vivo microdialysis in freely moving rats under various conditions. Both adenosine and an adenosine A₁ receptor agonist, 2-chloro-N⁶-cyclopentyladenosine, decreased extracellular 5-HT levels, whereas an adenosine A₁ receptor antagonist, 8-cyclopentyl-1,3-dimethylxanthine (CPT), and caffeine increased these levels. A selective A_2A receptor agonist (CGS-21680), an adenosine A₂ receptor agonist (PD-125944), an adenosine A₂ receptor antagonist, 3,7-dimethyl-1-propargylxanthine (DMPX), and an adenosine A₃ receptor agonist, N⁶-2-(4-aminophenyl)ethyladenosine (APNEA), did not affect extracellular 5-HT levels. When the adenosine A₁ receptor was blocked by CPT, the hippocampal extracellular 5-HT level was increased by adenosine, CGS-21680, and PD-125944, and decreased by caffeine, DMPX, and APNEA. When both adenosine A₁ and A₂ receptors were blocked by CPT and DMPX, the extracellular 5-HT level was decreased by adenosine, caffeine, and APNEA. The hippocampal extracellular 5-HT level was not affected by administration of APNEA alone, but was decreased by this agent when the adenosine A₁ receptor was blocked, irrespective of whether the adenosine A₂ receptor was functional. These inhibitory effects of adenosine, caffeine, and APNEA on extracellular 5-HT levels, during both adenosine A₁ and A₂ receptor blockade, were inhibited by selective 5-HT reuptake inhibitors. These results indicate that the stimulatory effects of the adenosine A₂ receptor and the inhibitory effects of the A₃ receptor on hippocampal extracellular 5-HT levels are masked by the inhibitory effects of the adenosine A₁ receptor.     

Differential expression of β-conglycinin genes in nodulated and non-nodulated isolines of soybean

Nodulated (T202) and non-nodulated (T201) isolines of soybean (Glycine max [L.] Merr.) were cultivated in a rotated paddy field in Niigata, Japan. The pods, and seeds were harvested at 7-day intervals until maturity, and the subunit compositions of seed storage proteins were analyzed by SDS-PAGE. The β-subunit of β-conglycinin could scarcely be detected in the non-nodulated isoline, T201, at any period throughout seed development, although it was a major component in T202. The accumulation of α′- and α-subunits of β-conglycinin, together with the acidic and basic subunits of glycinin, appeared about one week later in seeds of T201 than in those of T202, perhaps due to a shortage of nitrogen and growth retardation. Northern hybridization could not detect the β-subunit mRNA in immature T201 seeds, while it was pronounced in T202. These results indicate that the suppression of the β-subunit in the non-nodulating isoline T201 is regulated at the level of mRNA accumulation. The α′(α)-subunit mRNAs were actively expressed in both isolines. Total nitrogen concentration was consistently lower in T201 than T202. No significant difference was observed in either the free amino acid or ureide concentrations in seeds, although the concentration of sucrose was considerably lower in T201 seeds and pods compared with T202. This result indicates the possibility that β-subunit accunmlation was regulated not only directly by total nitrogen concentration but also by carbohydrate concentrations. Nitrogen regulation of storage protein subunit levels of soybean seed were evaluated using T201 and T202. Greenhouse-grown plants were subjected to different levels and timing of nitrate treatments. The culture solution (2, 5 or 10 mM NO₃–was supplied from flowering, 42 days after planting (DAP), until maturation (137 DAP), or switched from 2 to 10 mM, or from 10 to 2 mM at 61 DAP. With a continuous 2 mM NO₃–treatment, seed dry weight and N concentration of the T201 plants were significantly lower than those in the T202 plants due to the lack of N₂ fixation by the non nodulated T201 plants. However, when adequate NO₃ was supplied, N concentration and dry weight were similar in T201 and T202 seeds. When 5 mM NO₃ was supplied, the subunit proportion of the seed storage protein was similar in non-nodulating and nodulating isolines. On the other hand, when plants received a low level of NO₃ (2 mM), the β-conglycinin proportion was lower in T201 than in T2O2. Furthermore, in the nodulating T202 plants treated with 10 mM NO₃–the proportion of β-conglycinin increased markedly. The results indicate that non-nodulated T201 has a normal, non-defective, β-subunit gene and that limited N availability decreases accumulation of β-conglycinin, whereas high N availability increases the proportion of β-conglycinin in soybean seeds, irrespective of whether N was derived from N₂ fixation or from NO₃ absorption.     

Prostaglandin D2 metabolite stimulates collagen synthesis by human osteoblasts during calcification

We investigate the effect of the prostaglandin D₂ metabolite Δ¹²−PGD₂ (9−Deoxy−Δ⁹, Δ¹²−13,14-dihydroprostaglandin D₂) on collagen synthesis in human osteoblast. Δ¹²-PGJ₂ at 10⁻⁵M enhanced collagen synthesis in the presence of 2 mM α-glycerophosphate-2Na. The stimulative effect appeared as early as 3 days after addition and continued until 22 days. The enhancement of type I collagen synthesis was confirmed by polyacrylamide gel electrophoresis. The potency was the same as 10^1t-8M 1 α, 25 dihydroxy vitamine D₃ (1,25(OH)₂D₃). Northern blot analysis showed that 10⁻⁵M Δ ¹²-PGD₂ and 10⁻⁸M 1,25(OH)₂D₃ enhanced the transcribtion of type 1 procollagen (α₁) mRNA levels in osteoblasts.